Automobile transmission



Nov. 1, 1932. A. D. GARRISON 1,385,003

AUTOMOBILE TRANSMISSION Fild Dec. 14, 1951 Inventor? awfbwwz gm Patented Nov. 1, 1932 shame died December M, 1931. erial Kc. 53%,930.

My invention relates to the gear changing mechanism of an automobile, and the purposcs'of my improvements are: first, to provide a mechanism by which the gears may be :5 shifted automatically; second, to effect this automatic gear shift at predetermined and easily adjustable automobile speeds; third, to

f y a device which is so simple and reliable in that the entire operation of the automobile ma be made less complicated,and safer.

attain these objects by the mechanism illustrated in the accompanying drawing, in

Figure l is a section of the transmission mechanism; Figure 2 is a section of the means of control from'the accelerator pedal of the automobile; Figure 3 and Figure 4 are sec tions of the manual control mechanism so (i) is the transmission case which dorms the support for the gear-change mechanism and its lubricant. (2) is the shaft to which power is supplied from the motor and (i) and (16) are the shafts through which the 25 power is supplied to the wheels of the vehiole. A conntershaft drive gear (3) meshes with the main gear on the countershaft (4) and drives the countershaft which carries the second-speed countershaft gear 5), the first- 86 speed countershaft gear (6) an the reverse countershaft gear (7). The second-speed main-shaft gear (8), runs freely on bushings on the main shaft'and is in constant mesh with the gear 5) The sli ing gear (9) is splined to the shaft (10), and in the drawing is in mesh with the for the operation of the gear-shift mechafirst-speed countershaft gear 6), but it may be moved by the gear-shift mem or (13) ,either backward through a position of neutrality to a point where it meshes with the reverse car which is not shown, but situated just 'bac of the reverse countershaft gear (7) and in constant mesh with it; or the gear (9) may be through the pipe (25) to the cylinder (2d) shifted forward through a position of neutrality to the point where the rim gear on the forward portion of member (9 engages the clutch member (11) on the rear portion of the second-speed main-shaft gear (8) or the member (9) may be moved still farther forward through a position of neutrality to erform these operations quietly and easily, N

-or constraining means (14) exerts a conthe point where member engages the clutch member (12) on the main driyin shaft the teeth of the clutch member y'ast coinciding with the splineson the s i t he ear-shift member (13) is capable of sliding ackward or forward to efiect the motion of the gear member (9), and the spring straining force on the gear-shirt member tending to hold it in such a position that the gear member (9) is in the neutral position between the first and reverse gears, I

The function of shifting the gears is per formed by an hydraulic pump which exerts a pressure on the end of the rod (27) and opposite in direction to the force of the spring (14) (15) is a section of the case of the liquid pump. The pump is driven from the power-delivery shaft (16) throu h the worm and gear (17) and the vertical s aft (18).

The pump I prefer to use in illustratin my device is the simple gear type, in whic (19) represent the gears in mesh, (2%) the delivery tube through which the liquid in the case is delivered at high pressure to the space (21) from which it can escape back to the main body of liquid in the case by two paths: namely, by the orifice (22) orby the valve (24) The orifice (22) may be changed in size by the needle and adjustable screw (23) while the valve (24) may be adjusted to open at any predetermined pressure, Thus, irrespective of the speed which the shaft (16) may attain, the pressure in the pump will never exceed that necessary nism. At speeds below that necessary to open the valve (24)., the pressure of the liquid in the pump compartment (21) will vary with the speed and with the setting or the needle (23).

The hydrostatic pressure is conveyed and the rod (27) to the gear-shift member (13) of which the rod (27) isa part. Any leakage of the liquid along the cylinder walls from (26) is caught in the space (28) and drained back to the pump, case through the tube (29). r

By the adjustment of the needle (23), the liquid pressure may be made to oppose the force from the spring (14 and maintain the position of the gear-shi t member at any goint between neutral and high or direct rive through first and second respectively, but since it is imperative that gears shall be completely meshed before power is applied, a stepwise motion of the gear shift members is attained as follows:

Notches or surface irregularities are cut in the gear-shift member (13) at ositions corresponding to reverse, neutral, rst, second, and direct drives respectivel A ball (may be a roller or plunger) ts into the n0tches-1n the diagram, the ball is resting in the notch corresponding to first speed and is pressed down into the notch by the plunger (31) and the s ring (32). The tension of the s rin may he a justed by the nut (33), and t e .from rising at by the pm (34) which fits into a groove in the plunger when it is down. Thus when the pin (34) fits into the groove of the plunger (31), the ball (30) is held in the notch and prevents the motion of the gear-shift member. When the pin (34) is withdrawn from the groove, the plu1er and ball are free to rise provided th orce on the gear-shift member is suflicient to exert a force on the spring (32) and overcome it; if this is not the case, the gearshift metiflber will n(ot 31love. b'fhe coimpresdsion on e s r 32 may so a juste to the o sprin (14) and the slope of the side of the no in which the ball (80) rests that when a force is applied to the gear-shift release the ball, that force is just suflicient to maintain the position of the gear-shift member at the next highest notch. Thus, for example, first speed will not'be disengaged until the hydrostatic pressure from the pum 1s suficient to completely engage secon and second speed will not be disentil the ressure is sufiici'ent to com- 0 direct drive. But none will take place unless the pm (84) isthdr'awn from the groove of the anger (81).

a e gjom'tion of the pin (34) may be controlled y a manually operated device, but since automobile gears should be shifted only when power is not being delivered the transmission, I prefer to operate the pm either by attaching it to the'clutch throw-out of the automob' e in such a'm'anner the pin'is withdrawn only when the clutch is disengaged, or, the put from the accelerator or throttle of the motor in such a manner that the 'in is withof these drawn and the rs shifted -on y when the throttle is w connection, as I prebeg! if to it, is illustrated in the drawing, in

unger may be prevented member which is just suflicient to better, to operate (35) is a flexible cable b which the pin may be released; this flexib e cable leads to the floor boards of the automobile (36) where the cable is. attached to the lever (38) and the support (37). The lever (38) is normally he d down in the position illustrated in the drawing, in which position the pin (34) engages t e groove in the plunger (31). This position is obtained by the compression of the spring (39). The accelerator pedal (40) has its stem extending through a hole in the lever 38) and a collar (41) is fitted to the stem at such a position that it lifts the lever (38) just as the throttle closes. Thus the automatic gear-shift mechanism can operate only with the throttle in the closed osition.

Since it is necessary to s ift the gears from neutral to reverse, or from neutral to first speed while the automobile is standing still; and since it may be desirable to lock the transmission in one of the forward 5 eeds until it is desired to release it, I provide the following mechanism:

The flexible cable control and rod (42) is attached,to the ear-shift member (13) and leads through t e,cable sheath (43) to the handle (44) which may be located on the dash, on the steering 0st, or at any convenient place. Thehand e (44) is free to move up or down with the motions of the arshift member, or it may be locked in any of the forward speeds by turning the handl so that'the pin (45) enters one of the w: behind one of the ball-and-spring locks (46). With the pin turned into oneof the recesses, the gear'remains meshed at that speed until the handle is turned back and the gear-shift member released. v

v I- prefer to use this automatic automobile transmission in conjunction with an over- 106 running clutch or free wheeling unit which is indicated at (47). With the over-running clutch the operation of the tron is simplified and in driving the automobile the following results may be attained:

The motor is started with the handle (44) in the neutral position. If one desires to reverse, the clutch is disengaged and the handle (44) pushed in to the reverse position where it will remain until ulled out. If one desires to start forwar the clutch is disen god and the handle 44) ulled out to the it-speed position. orce of the spring (14) should not be enough to release t e gear-shift member from this firstposition,'but if the handle (44) shoul be drawn too far, say to the second-speed notch or the direct drive. notch, the spring (14)- would immediatelyreturn the members to thefirst-speed position. a

When the clutch is engaged and the automobile starts, the liquid pressure in the pum ns to oppose the action of the spring (14 and rises in proportion to the speed of the y, vehicle; but during the acceleration, the no run *ooint, the pressure will he too low to release the ball and the first speed remains meshed. The exact speed for release'wonid he adjustable at the valve needle (23).

The gear mechanism would not he released from the second-speed position until a syeed of, say, ten to twelve miles per'hour, aoove which speed the direct drive would mesh at any time the accelerator pedal is released.

Above, say, twenty miles per. hour, the valve (24.) opens sothot the liquid pressure would not reach excessive values at high speeds.

As the automohile is reduced in speed, the

direct drive ohtains until the accelerator pedal is released at a speed below, say, live miles per'hour, where the spring (14) makes the hall unstable in the direct-drive notch and pushes the gear shift members to the second-speed position. ust before the automobile stops, the members return to the firstspeed position for the suhsequent start.

Thus, in combination with an over-mmning clutch, the gears shift automaticolly without attention merely on the release of the accelerator-pedal. lln the absence of an over-running clutch, or when the over-running clutch is locked out, it would he necessary to declutch to sheet the automatic shiit,

since the strain on the gears would check their motion;

For the liquid in the hydraulic pump 1 prefor to use some substance comhining some lubricating properties with relatively high and with as low temperature coeifi oil viscosity as goossihle. Since, however, liquid used for this nurpose "would here its viscosity reduced by increasing teingzerature, and since the srlliustment of the soeedchange mechanism will depend on the riscosity or the liquid, ii gorovide the followand the orifice is made smaller to correspond with the reduced viscosity of the liquid. By a suitable adjustment of the shape of the vane and the orifice, the length and composition of the bimetallic (or multimetallic) element, and the combination of several elements and several orifices, the proper amount of compensation may be provided for the changing characteristics of the material to be pumped with changing temperature.

I amaware that my invention can he operated successfully with a pump ofa conventional centrifugal design, or by a plunger pump, or a cylinder pump; therefore, in drafting my claims, I shall define the term pump to claim and include any well-known mechanical device for creating a, difierence of pressure in a plastic material, and I shall define and claim the term plastic material to include any suhstance, Whether gas,

liquid, or mixture of liquid and solid, whose shape is so easily molded that pressure is readily transmitted from one part of the material to another in all directions.

1 claim:' I w 1. In an automatic automobile transmission, means for transmitting power through a plurality of soeed ratios,-a movable shift member being instrumental in the change from onespeed ratio to'another, means con- I straining the said shift member toward the position where power is transmitted at low speed; means for eiiecting the motion of the said shift member to a position where power is transmitted at high speed comprising a plastic materiel, s pump, means for operating the pump and means communicative. hetween the said plastic material and the said shift member; means for limiting the movement of the shift member to predetermined automobile speeds comprising a memher having surface irregularities, an irregularityenr aging element, means engaging the said irregularity-engaging element with the said surface irregularities whereby movement of the said shift member can occur only by displacement of the said irregularityengaging element, means for adjusting the force of engagement of the said irregularity-engaging element relative to the force of the said means constraining the shift mem her end means for adjusting the pressure of the sol pisstio materiel relative to the speed of the automobile and reletive to the force of thesaid means constraining the shift memher whereby the nressu're of the said plastic ment of the shiftmemher and to change the speed ratio at a predetermined outomohzle' speed.

2.. in; an automatic automohile transmis sion, the cornhination of a driving shaft, a Cl'fWrE-Li shaft, o co-ontershaft, gesr members disposed on the said shafts, a movable gear member disposed on one of the said shafts whereb the driving shaft engages the driven shaft t rough difi'erent gear members when 5 the said movable gear member is moved to different ositions, a gear-shift member engaging t e said movable gear member, a spring exerting a force on the gear-shift member in the opposite direction from engagements which effect the highest speed ratio of driven shaft to driving shaft. a notchengaging element, a spring constraining the notch-engaging element toward notches disposed on the movable gear-shift member whereby the notch-engaging element engages the notches when the said movable gear mem-v her is in positions engaging diflerent speed ratios and whereby a substantial force is required to disengage the notch-engaging element, a ump, communicative means from the driven s aft to the ump, a plastic material disposed in the sai pump, means for communicating a force from the plastic material to the said movable gear member. the said force varyin with the speed of the driven element, ten ing todisengage the notch-enga 'ng element and tending to displace the sai movable gear member toward the engagements which efi'ect the highest speed ratio of driven shaft to driving shaft, a locking element whereby the notch-engaging element is prevented from disengaging, and means for mafiring the locking element inoperative at W1 3. The structure of claim (1) and a look ing device comprising a member which in its normal osition prevents the disengagement of the 881d irregularity engaging element and means for displacing the said member and 4 making the locking device inoperative at will. 4. The structure of claim 2) and cc-operative means between the accelerator pedal of the automobile and the said locking device whereby the depression of the accelerator pedal efiects the engagement of the said member, and the release of the accelerator pedal effects the disengagement of the said member. 4

5. The structure of claim (2) and communicative means from the said locking element to the accelerator pedal of the auto- ,mobile' whereby the release of the accelerator pedal causes t e locking element to become inoperative.

6. The structure of claim (1) andmeans for shifting and locking the said gear-shift member comprising: shaft, a handle on the shaft, a flexi le ca -le attached to the shaft 9 and to. the gear-shift member, support for the shaft, a pin on the shaft adapted to engage us" handle when the pin is turned into one of the r 1n the shaft support and to lock the a 7.0 of claim (1) and a valve, I

changes in temperature alters the dimensions of the said ori .ce.

9. In an automatic automobile transmis= sion the combination with a speed-change mechanism of a plastic material, means for maintaining the said plastic material at'pressures which change with changing automobile speeds, means for operating the speedchange mechanism of the automobile by the piessure of the said plastic material, a memr having an orifice through which the said plastic material ma flow, a multimetallic strip capable of bending under the influence of chan s in temperature, said stri dissed re ative to the said orifice whereby the ending of the said strip aiters the dimensions of the said orifice.-

ALLEN DARNABY GARRISON.

cenrmcnre er eernnec'nen.

PM n. neseeos. November m2.v

ALLEN nmnmnr stangrson.

' it is hereby certified that error appears in the printed specification of the abeve numbered patent requiring correction as fellows: Page 4 line 42, ciaim 4, strike out theenciesed figure "(2)" and insert instead "(1) and a iecking device ccinpr-ising a member which in its normal nositicn prevents the disengagement cf the said irregniarity-engaging eiement and means {or disniac'ing the said member and making the inciting device inoperative at wi'ii,"; and that the said Letters htent siieuld be read with this correction therein that the same may ccnform to the recerd at the case in the Patent @iiice ignen and seated this 3rd day cf January, A. D. 1933.

(seal) Acting iiommis'sioncr of Patents; 

